Aha, for static Makefile GG added ...

+$(NASM_BLD)/%.obj: src/x86/%.asm
+       $(NASM) -f elf64 \
+               -I src/ -I $(BUILD)/ -MQ $@ -MF $@.ndep \
+               $< -o $@

replace elf64 with elf32 for 32-bit builds ..... (looking at my source folder for 32-bit libdav1d build via Meson/Ninja)

actually there are two instances of this parameter, another for (libdav1d) testfiles down the file ....


+$(TESTS_CHKASM_BLD)/x86/%.obj: $(TESTS_CHKASM)/x86/%.asm
+       @$(NASM) -f elf64 \
+               -I src/ -I $(BUILD)/ -MQ $@ -MF $@.ndep \
+               $< -o $@